Lets breakdown what causes water spots in the first place.
First you start with the actual droplets
Then, the evaporation process removes the water and leaves behind the concentrated chemical compounds. Like calcium
If your vehicle is left out in the sun to dry..The sunlight is magnified by the curve of the bubble and really starts to work on pitting underneath the paint by evaporating the water and concentrating the leftover chemical compounds...especially acid rain.. This is where you want a good wax job but no beading.
So how do you help get rid of them.
1. try to prevent them from happening before hand by using a water softening rinsing agent or spray that reduces beading. I put some in a spray bottle and after a rain I squirt 2 or 3 times over the top of my truck and BAM...the water lays down and rolls off.
2. If you have spotting already...Start light and work towards heavy meaning...try wax then move to clay then move to machine.
Hope this helps...Good luck!